Jonathan Turley is the Shapiro Professor of Public Interest Law at George Washington University.

President Trump is reportedly looking into using his pardon power in response to an expanding special counsel investigation of Russian influence in the 2016 election. If he really did pardon his aides, his family or himself to head off Robert Mueller’s inquiry, the move probably would be constitutional but ultimately self-defeating for the president.

In using his power to pardon potential witnesses against him, Trump probably would convert a weak criminal investigation into a full-fledged impeachment effort. In 1833, Chief Justice John Marshall upheld a presidential pardon by Andrew Jackson by saying that a pardon is “an act of grace” by a president. A pardon in these circumstances would not be viewed as an act of grace, but a gratuity from an isolated president.

Trump clearly possesses the authority to pardon associates and family members under Article II, Section 2 of the U.S. Constitution, which states that the president “shall have power to grant reprieves and pardons for offenses against the United States, except in cases of impeachment.” Although presidents have tended to wait for convictions before issuing pardons, Trump can do so in anticipation of federal charges. In Ex parte Garland in 1866, the Supreme Court ruled that the pardon power “may be exercised at any time after its commission, either before legal proceedings are taken, or during their pendency, or after conviction and judgment.” That is precisely what Gerald Ford did when he pardoned Richard Nixon before any charges were brought against him.

The issue of whether a president can pardon himself is one of the unanswered questions of the Constitution; it has never happened in the history of our republic. Even Nixon did not stoop to a self-pardon, although he did research it. Neither did Andrew Johnson or Bill Clinton, both of whom were impeached by the House but not removed from office by the Senate. Such an act would make the White House look like the Bada Bing Club. After a self-pardon, Trump could wipe out the Islamic State, trigger an economic golden age and solve global warming with a carbon-eating border wall — and no one would notice. He would simply go down in history as the man who not only pardoned his family members but himself.

Pardoning his associates at this stage would clearly have a tactical benefit, but the historical and political costs of that would be immense. The most obvious reason for issuing pardons now would not be to protect any of the key people from jail but to limit Mueller’s leverage over witnesses. Mueller has selected a team of prosecutorial heavies, some of whom are known for flipping witnesses and using pressure to secure their cooperation. A pardon removes that option and reinforces the ability of close associates to take a hard line with investigators.

Of course, the use of the pardon power to protect the president’s political allies and family members would be legitimately decried as an abuse. It would not, however, be unprecedented.

President Thomas Jefferson pardoned Jeffersonian Republicans accused of treason under the Alien and Sedition Act. He also issued a pardon for Erick Bollman that would have allowed Bollman to testify against Aaron Burr in 1807. Jefferson and Burr had received the same number electoral votes for the presidency (a tie broken by Alexander Hamilton, whose own conflicts with Burr would later lead to the duel in which Burr killed him). After Burr became vice president, Jefferson wanted Bollman to testify against Burr for alleged treason in plotting with the British to create a new country out of territory in the Southwest and Mexico. Bollman, however, refused to accept the pardon and thus did not testify.

The most recent abuse of pardon power was by Clinton. He waited until his last day in office to pardon billionaire Marc Rich, generally considered one of the least worthy recipients of a pardon in history. Jimmy Carter denounced the abuse of the pardon power for Rich as “disgraceful” and attributed Clinton’s decision to “his large gifts.” Worse yet, on the same day, Clinton pardoned his half-brother, Roger Clinton, in an open abuse of pardon power to benefit his family.

Trump could attempt to justify pardons on the basis that any mistakes committed last year were simply the result of novice aides unfamiliar with politics. After all, in 1795, George Washington pardoned the leaders of the Whiskey Rebellion, justifying his decision by dismissing one of them as “little short of an idiot.” The idiot rationale, though, does not sit well with Trump’s “anyone would have taken that meeting” defense. Nor would it be in keeping with Trump’s carefully maintained public image of himself and his children.

Some of Trump’s aides could obviously use a pardon. Paul Manafort and Michael T. Flynn are facing credible claims of violating the Foreign Agents Registration Act.However, FARA violations are almost uniformly addressed administratively, not through criminal prosecutions. Indeed, there have been only three prosecutions under FARA since 1966, when the law was last revised. Nevertheless, prosecutors could threaten a FARA charge to induce cooperation. Likewise, Donald Trump Jr. and Jared Kushner will be questioned before congressional committees starting next week; the risk of false or misleading statements will be at their apex. One such false statement to investigators can be charged as a violation of 18 U.S.C. 1001, or a false statement under oath to the committees can be charged as perjury. That can be considerable leverage for prosecutors.

But pardons would not end the investigation. Even if everyone were pardoned, Mueller could — and probably would — issue a report to Congress. Likewise, the congressional investigations would continue. Indeed, with pardons, witnesses could lose protections against self-incrimination and could more easily be forced to testify. New crimes such as perjury could fall outside of the pardon, and such a pardon would not protect against state charges. Finally, the difference could be that the focus would shift from potential counts for indictment to counts for impeachment. That change is not an improvement. The existing claims of criminal conduct on Trump’s part are relatively weak and speculative. To move from the legal to the political forum is to leave strategic high ground for a quagmire.

Tactical pardons are like burning bridges to slow an investigation. That has rarely stopped a determined foe. Indeed, it tends to encourage and swell the ranks of opponents.

In the end, a pardon of Trump’s allies and family — let alone himself — would destroy any legacy of Trump’s and demean his office. The presidential pardon remains one of the most majestic and storied powers of our Constitution. Hamilton once stated that the unfettered power given to a president reflects its foundation in “humanity and good policy.” Neither would justify pardons at this stage of the investigation.